NAME

       sleepenh - an enhanced sleep program.

SYNOPSIS

       sleepenh [initial-time] sleep-time

DESCRIPTION

       sleepenh  is  a  program  that  can be used when there is a need to execute some functions
       periodically in a shell script. It was not designed to be accurate for a single sleep, but
       to be accurate in a sequence of consecutive sleeps.
       After a successful execution, it returns to stdout the timestamp it finished running, that
       can be used as initial-time to a successive execution of sleepenh.

OPTIONS

       There are no command line options. Run it without any option  to  get  a  brief  help  and
       version.

ARGUMENTS

       sleep-time is a real number in seconds, with microseconds resolution (1 minute, 20 seconds
       and 123456 microseconds would be 80.123456).
       initial-time is a real number in seconds, with microseconds  resolution.  This  number  is
       system  dependent.  In  GNU/Linux  systems,  it  is  the  number of seconds since midnight
       1970-01-01 GMT. Do not try to get a good value of initial-time. Use the value supplied  by
       a previous execution of sleepenh.
       If you don't specify initial-time, it is assumed the current-time.

EXIT STATUS

       An exit status greater or equal to 10 means failure.  Known exit status:

       0      Success.

       1      Success.  There  was  no  need  to sleep. (means that initial-time + sleep-time was
              greater than current-time).

       10     Failure. Missing command line arguments.

       11     Failure. Did not receive SIGALRM.

       12     Failure. Argument is not a number.

       13     Failure. System error, could not get current time.

USAGE EXAMPLE

       Suppose you need to send the char 'A' to the serial port ttyS0 every 4 seconds. This  will
       do that:
               #!/bin/sh
               TIMESTAMP=`sleepenh 0`
               while true; do
                 # send the byte to ttyS0
                 echo -n "A" > /dev/ttyS0;

                 # just print a nice message on screen
                 echo -n "I sent 'A' to ttyS0, time now is ";
                 sleepenh 0;

                 # wait the required time
                 TIMESTAMP=`sleepenh $TIMESTAMP 4.0`;
               done

HINT

       This program can be used to get the current time. Just execute:

       sleepenh 0

BUGS

       It is not accurate for a single sleep. Short sleep-times will also not be accurate.

SEE ALSO

       date(1), sleep(1).

AUTHOR

       This manual page was written by Pedro Zorzenon Neto.

                                            2008/04/20                                SLEEPENH(1)